The present application is somewhat related to the U.S. patent application of applicants"" Ser. No. 09/832,454 and 09/832,434 filed of even date herewith. The contents of these somewhat related applications are hereby incorporated by reference herein.
As set forth in applicant""s above identified patent document 09/832,454, when conducting military operations, and particularly airborne military operations, against an underground hardened target it is often difficult to assess the degree of success achieved in neutralizing the target from further enemy use.
In addition to the difficulty arising from the underground and hardened nature of many present day targets it may be appreciated that the gathering of target damage assessment information is often accomplished from a distant and moving vantage point, i.e., from a moving aircraft, an aircraft that has not approached or has not remained in the target area because of concern for its own safety from ground fire or other hostile threats. Moreover such target damage assessment is often desired in the situation wherein neither the attacking nor the assessing aircraft has been within viewing distance of the target during the entire operationxe2x80x94but has remained over the horizon or at some safe distance from the target and its probable defenses during both the weapon launch and success assessment phases of the operation. In any event it is clearly not desirable to require the attack aircraft or any related aircraft to either remain in the target vicinity for assessment purposes or for the aircraft to be required to return to the target area for assessment purposes or for a second neutralization attempt-particularly if such a second neutralization is not needed.
As a remedy for this success assessment difficulty the 09/832,454 document has disclosed a system for collecting tangible objective target arrival experience data from the warhead device itself and for making this data available at a remote mission analysis center or available to the pilot of the mission aircraft or to some other aircraft. One of the more technically challenging aspects of this data collection sequence resides in the provision of an antenna apparatus capable of satisfactory electrical performance and physical endurance in the subterranean as well as the airborne phases of a warhead delivery sequence. In addition the large deceleration forces expected in the course of a warhead arriving at the desired detonation point within the interior of a hardened underground target there are significant other environmental challenges to be tolerated by such an antenna. The present invention is believed to provide an attractive resolution of these difficulties.
The present invention provides a physically rugged ultra high radio frequency antenna suitable for both carriage on an airborne warhead weapon and for use during a subsequent subterranean travel and deceleration impact inclusive intervals of the warhead. The antenna invention particularly includes structural and electrical attributes responsive to harsh environmental conditions.
It is therefore an object of the present invention to provide an ultra high radio frequency antenna capable of being mounted in the limited confines of a guidance tail kit attached to a munitions warhead device.
It is another object of the invention to provide an ultra high radio frequency antenna that is capable of withstanding the physical abuse attending a high-speed penetration of multiple tens of feet of earth and reinforced concrete layers by a penetrating warhead device.
It is another object of the invention to provide an ultra high radio frequency antenna remaining electrically usable notwithstanding presence in a dielectrically changing debris field of additionally varying electrical properties.
It is another object of the invention to provide a process by which an antenna meeting these objects can be fabricated without expensive machining.
It is another object of the invention to provide an apparatus capable of accommodating a transitional airborne to subterranean impact shock environment while functioning as an ultra high frequency antenna apparatus.
It is another object of the invention to provide a xe2x80x9ccone monopolexe2x80x9d extension of the monopole antenna, an antenna suitable for use under extreme environmental conditions.
These and other objects of the invention will become apparent as the description of the representative embodiments proceeds.
These and other objects of the invention are achieved by ruggedized transitional airborne to subterranean environment ultra high frequency antenna apparatus comprising the combination of:
an electrically conductive ground plane member disposed on a rearward portion of an air deliverable earth and concrete penetration military weapon and including an aperture opening in a central portion thereof;
a layer of electrical insulation material sufficient to decouple said ground plane from a body portion of said military weapon and preclude excessive weapon nose-directed radiation;
an electrically conductive radiating element of ultra high frequency tunable length, disposed normal to said ground plane, located at said central portion aperture opening and extending rearward of said military weapon device;
said electrically conductive radiating element having both an inverted upstanding conical shape with a conical apex electrical node disposed at said central portion aperture of said electrically conductive ground plane member but in electrical isolation therefrom and having a conical base portion disposed substantially parallel with and separated from said electrically conductive ground plane member;
said electrically conductive radiating element being comprised of porous electrically conductive material disposed in a closed conical surface geometric configuration;
a mass of cured resin dielectric material surrounding, embedding and impregnating said porous radiating element and extending from a radiating element-adjacent face of said electrically conductive ground plane member rearward of said military weapon device;
said mass of cured resin dielectric material also surrounding, embedding and impregnating a porous element comprising said ground plane member and additionally including a portion extending forward along said military weapon and supporting transmitter electronics apparatus of said military weapon device;
said cured mass of dielectric material having a dielectric constant greater than that of air and tending to increase an effective electrical length characteristic of said electrically conductive conical shape radiating element in excess of a physically-determined nominal ultra high frequency electrical length characteristic thereof;
said cured mass of resin material also having external physical shape and dimensions compatible with surrounding portions of said military weapon device and compatible with earth and target penetration deceleration forces predicted for said military weapon device.